This invention relates generally to a system for simulating missile target motion. More particularly the invention relates to a mechanical device especially adapted to reflect a collimated beam of radiation along an optical path with two mirrors, in two planes in a precise manner.
In the past, the simulation of target motion in missile testing has involved mechanically positioning the target in front of the missile, or, in the case of an infrared guided missile, mechanically positioning a set of mirrors to reflect the target image from a fixed source to the missile. Apparent target motion is accomplished by moving one or more mirrors in one or more planes and maintaining an optical path from the source to the missile. Each mirror must be positioned in a manner such taht the mirror reflects the image, beam, or light ray according to the law of mirror reflection, viz. : the angle of incidence is equal to the angle of reflection. Accordingly, the angle between the incident and reflected rays is twice the angle of incidence, and the normal line to the plane of the mirror bisects this angle. The task of precisely directing a reflected image or beam involves positioning the mirror such that the normal to the mirror bisects the subtended angle between the source of the beam and the desired position of the beam. Each mirror must, therefore, be positioned in two planes requiring calculations in a suitable space coordinate system. These calculations require a substantial amount of time to determine. Additionally elaborate, graduated mechanical devices are required to incorporate the calculations into a mirror steering system.